1. Field of the Invention
The present invention generally relates to electronic circuits, and more particularly to current mode drivers.
2. Description of Related Art
High-speed data transmitters in modern communications equipment employ current mode drivers for driving a voltage swing of a differential output signal. A current mode driver drives a voltage swing of a differential output signal by driving a differential current through a pair of resistive loads. The current mode driver typically includes a current source and a current mirror for generating a tail current. In operation, the current mode driver channels the tail current through a differential pair of transistors based on a differential input signal to generate the differential current.
Although a current mode driver provides significant advantages over some other types of drivers in terms of switching speed, a current mode driver is susceptible to integrated circuit process variations, supply voltage variations, and operating temperature variations. Such variations in process, voltage, and temperature may affect the amplitude, phase, and frequency of the differential output signal generated by the current mode driver. In particular, these variations may affect a voltage swing of the differential output signal, which may reduce the integrity of the differential output signal.
In light of the above, a need exists for a current mode driver that generates a differential output signal having a constant output voltage swing.